(Refer: Mandatory Appendix 12 (Page 435) of ASME BPVC Section VIII Div 1, 2017 Edition.)
(a) Indications characterized as cracks, lack of fusion, or incomplete penetration are unacceptable regardless of length.
(b) Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths that exceed:
- 6 mm (1/4 in.) for T up to 19 mm (3/4 in.)
- T/3 for T from 19 mm to 57 mm (3/4 in. to 21/4 in.)
- 19 mm (3/4 in.) for T over 57 mm (21/4 in.)
where T is the thickness of the weld excluding any allowable reinforcement. For a butt weld joining two members having different thicknesses at the weld, T is the thinner of these two thicknesses. If a full penetration weld includes a fillet weld, the thickness of the throat of the fillet shall be included in T.